1. Field of the Invention
The present invention relates to lockout circuits for use in electrically operated and controlled multiple column vending machines, wherein the vending machines are actuated by the deposit of coins, and the selecting and dispensing of the product is accomplished by logically operated control elements within the machine. More specifically, the invention relates to several embodiments of lockout circuitry which function to permit continued operation of the multiple column vending machine in the event of a malfunction of a particular column.
2. Description of the Prior Art
Electrically operated multiple column vending machines including lockout features are well known. Over the years the vending machine industry has developed a number of machine circuit configurations directed towards providing economical and reliable lockout means to assure the fullest possible utilization of their vending machine capabilities. Thus, while the problem of having a multiple column machine rendered completely inoperative due to failure of a single column has received considerable effort, the lockout mechanisms proposed and employed invariably include a significant amount of additional electrical and mechanical devices over non-protected counterpart machines. The additional components in themselves contribute to lowering the overall reliability of the machines due to the increased complexity introduced. Various conventional solutions to the jammed column lockout condition show the inclusion of additional electrically operated/mechanically interlocked relays for each product column, while other earlier attempts included mechanical interlocking means. Exemplary prior art approaches may be found in the Breeden U.S. Pat. No. 3,669,235 and the Bowman U.S. Pat. No. 3,486,601. Therefore, while the prior art shows considerable effort directed toward providing the malfunction lockout capability, it is clear that a completely satisfactory approach has yet to be developed.